There were two constants here, `INLINE_ONEBOX_LOADING_CSS_CLASS` and
`INLINE_ONEBOX_CSS_CLASS` that were both longer than the strings they
were DRYing up: `inline-onebox-loading` and `inline-onebox`
I normally appreciate constants, but in this case it meant that we had
a lot of JS imports resulting in many more lines of code (and CPU cycles
spent figuring them out.)
It also meant we had an `.erb` file and had to invoke Ruby to create the
JS file, which meant the app was harder to port to Ember CLI.
I removed the constants. It's less DRY but faster and simpler, and
arguably the loss of DRYness is not significant as you can still search
for the `inline-onebox-loading` and `inline-onebox` strings easily if
you are refactoring.
